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Renesas 71256S35TDB
- Part No.:
- 71256S35TDB
- Manufacturer:
- Renesas
- Category:
- Memory
- Package:
- 28-CDIP (0.300", 7.62mm)
- Datasheet:
-
71256S35TDB.pdf
- Description:
- IC SRAM 256KBIT PARALLEL 28CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,068
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Product details
Overview
71256S35TDB from Renesas is a 256K (32K × 8-bit) high-speed CMOS static RAM with 35ns max address access time, TTL-compatible I/O, and military-grade reliability compliant to MIL-STD-883 Class B. It operates across –55°C to +125°C, consumes 135mA dynamic current at 5V, and features automatic low-power standby when CS is HIGH - used in avionics data buffers and ruggedized telemetry systems.
For engineers reviewing the 71256S35TDB datasheet, 71256S35TDB pinout, 71256S35TDB application, or 71256S35TDB equivalent, key selection criteria include military temperature support, ceramic DIP package compatibility, chip-select–controlled power-down behavior, and verified 2V data retention capability in L-version variants.
Technical Context
This device implements a fully decoded 15-bit address space (A0–A14) driving a 262,144-bit memory array with bidirectional 8-bit I/O (I/O0–I/O7). Its control logic uses three independent enables - CS for device selection, WE for write strobing, and OE for output gating - enabling flexible read/write timing under both CS- and WE-controlled cycles.
The 71256S35TDB supports two distinct standby modes: TTL-level standby (ISB) when CS > VIH, drawing 20mA, and full CMOS-level standby (ISB1) when CS > VHC, drawing only 20mA - no battery backup function (reserved for L-version), and no internal voltage regulation or refresh circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Organization | 32K × 8-bit (262,144 bits), fixed parallel interface - no internal banking or burst mode. |
| Access Time (tAA) | 35ns max at VCC = 4.5–5.5V, TA = –55°C to +125°C - defines minimum clock-to-data latency in synchronous systems. |
| Supply Voltage | 5.0V ±10% (4.5–5.5V) - requires stable regulated 5V rail; not 3.3V tolerant. |
| I/O Compatibility | TTL-input and TTL-output compatible - interfaces directly with 74LS/ALS logic without level shifters. |
| Operating Temperature | –55°C to +125°C (military grade) - validated per MIL-STD-883 Class B screening. |
| Power Dissipation | 135mA dynamic ICC (typ. 350mW at 20ns speed); 20mA ISB standby - thermal design must accommodate 1W peak. |
| Package Type | 28-pin 300-mil ceramic DIP (SD28) - hermetically sealed, leaded, through-hole mountable. |
Pinout & Package
71256S35TDB is housed in a 28-pin 300-mil ceramic dual in-line package (CERDIP), designated SD28 per Renesas ordering nomenclature. The package provides hermetic sealing and thermal stability for extended operation in harsh environments.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit unidirectional address bus; latched on CS/WE transitions - no internal address multiplexing. |
| I/O0–I/O7 | Data Input/Output | Bidirectional 8-bit data bus; high-impedance when CS HIGH or OE HIGH - supports shared bus architectures. |
| CS | Chip Select | Active-low enable; drives device into low-power standby when HIGH - primary power control signal. |
| WE | Write Enable | Active-low write strobe; initiates write cycle when CS and WE both LOW - controls data latch timing. |
| OE | Output Enable | Active-low output gate; disables outputs (high-Z) when HIGH - isolates data bus during reads/writes. |
| VCC | Power Supply | +5V supply pin; bypass capacitor required near pin for noise suppression in high-speed operation. |
| GND | Ground Reference | Signal and power ground return; must be low-inductance connection to minimize switching noise. |
Key Features
| Feature | Design Value |
|---|---|
| MIL-STD-883 Class B compliance | Qualified for military applications including vibration, shock, and temperature cycling per standard - eliminates need for additional qualification testing. |
| Automatic standby on CS deassertion | Reduces system power by >90% when CS goes HIGH - enables rapid entry/exit from low-power state without external sequencing. |
| TTL-compatible I/O levels | Direct interface with legacy 5V logic families (e.g., 74LS, 74F) - eliminates level translators in retrofitted systems. |
| Hermetic 300-mil CERDIP package | SD28 package ensures long-term reliability in high-humidity, high-radiation, or vacuum environments - typical for aerospace deployments. |
| Read/write cycle timing independence | Supports both CS-controlled and WE-controlled write cycles - allows flexible integration with diverse bus controllers and FPGA glue logic. |
Applications
| Avionics Data Buffering | Tactical Radio Memory |
|---|---|
|
Use Scenario: Real-time buffering of sensor telemetry packets in flight control computers where deterministic latency and radiation tolerance are critical. IC Role / Device Role / Timing Role: Standalone parallel SRAM providing zero-wait-state storage for ADC sample streams and command queue management. Use Value: 35ns tAA ensures sub-40ns data capture window alignment with 25MHz sampling clocks; MIL-STD-883 qualification guarantees operation at altitude and under EMI stress. |
Use Scenario: Storing encrypted voice frames and protocol stack state in handheld military radios operating across extreme ambient temperatures. IC Role / Device Role / Timing Role: Non-refreshing memory holding volatile session data between encryption engine bursts and RF transmit windows. Use Value: –55°C to +125°C rating enables uninterrupted operation in desert or arctic conditions; 28-pin CERDIP resists thermal cycling fatigue better than plastic packages. |
| Secure Boot ROM Shadow | Ruggedized Industrial PLC |
|
Use Scenario: Mirroring boot firmware from slow serial flash into fast parallel memory during cold start in secure embedded systems. IC Role / Device Role / Timing Role: High-speed shadow RAM mapped into processor's reset vector space for immediate code execution post-power-on. Use Value: TTL-compatible I/O allows direct connection to legacy microcontroller buses (e.g., Intel 80C188); 35ns access avoids pipeline stalls during first instruction fetch. |
Use Scenario: Holding real-time I/O mapping tables and motion control trajectory buffers in factory-floor programmable logic controllers exposed to oil mist and wide thermal swings. IC Role / Device Role / Timing Role: Deterministic-access scratchpad memory for cyclic executive tasks requiring guaranteed worst-case response times. Use Value: Hermetic SD28 package prevents corrosion from industrial contaminants; MIL-qualified timing specs ensure consistent performance despite voltage droop or EFT events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar static RAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CY62256LL-55ZXC | 55ns access, 32K × 8, 5V, SOIC-28 - slower, plastic package, commercial temp only (0°C to +70°C). | Lacks military qualification, hermetic seal, and extended temperature range - unsuitable for avionics or field-deployed systems. | Select only for cost-sensitive, non-ruggedized industrial control boards where 55ns latency is acceptable. |
| AS6C4008-35TIN | 35ns access, 512K × 8, 3.3V/5V tolerant, TSOP-32 - higher density, lower voltage, different pinout and package. | Requires PCB redesign (32-pin TSOP vs. 28-pin DIP), level-shifting if interfacing with pure 5V logic. | Consider for new designs needing higher density and lower power, but not for drop-in replacement or legacy board repair. |
Compared with 71256S35TDB, CY62256LL-55ZXC trades military reliability and speed for cost and availability, while AS6C4008-35TIN offers greater capacity and modern packaging at the expense of pin compatibility and 5V-native operation - making 71256S35TDB irreplaceable in fielded MIL-SPEC hardware.
Availability
71256S35TDB is available at Aetrix Electronics and suitable for avionics data buffering, tactical radio memory, and secure boot ROM shadowing requiring stable component supply across extended product lifecycles.
Supply support for 71256S35TDB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Renesas Electronics Corporation is a global semiconductor leader specializing in microcontrollers, analog, power, and memory solutions for automotive, industrial, and infrastructure markets.
The 71256S series belongs to Renesas' legacy high-reliability SRAM product line, designed specifically for military, aerospace, and industrial applications demanding extended temperature operation and MIL-STD-883 qualification.
FAQ
What is the maximum operating temperature range supported by the 71256S35TDB?
The 71256S35TDB is rated for operation from –55°C to +125°C and is fully qualified to MIL-STD-883 Class B for military applications. This specification is confirmed in the Absolute Maximum Ratings and Recommended Operating Conditions tables of the Renesas datasheet revision Aug.06.20. No derating is required within this full range, and the 71256S35TDB maintains its 35ns access time guarantee across the entire span.
Does the 71256S35TDB support battery backup or data retention below 5V?
No, the 71256S35TDB does not support battery backup or low-voltage data retention. That capability is exclusive to the 'L' (low-power) variant family, such as 71256L35TDB, which specifies 2V data retention. The 71256S35TDB is the standard-power version and requires a stable 5V supply for all operations, including standby - its ISB current is 20mA, not µA-scale.
Is the 71256S35TDB pin-compatible with other members of the 71256 family?
Yes, all 71256S and 71256L variants in the SD28 (300-mil CERDIP) package share identical pinout and footprint, including 71256S25TDB, 71256S45TDB, and 71256L35TDB. Signal assignments (A0–A14, I/O0–I/O7, CS, WE, OE, VCC, GND) are invariant across speed grades and power variants in the same package - enabling speed binning or power optimization without PCB change.
What package type does the 71256S35TDB use, and is it RoHS-compliant?
The 71256S35TDB uses a 28-pin 300-mil ceramic dual in-line package (CERDIP), identified as SD28 in Renesas ordering nomenclature. Per the Aug.06.20 datasheet, "Green parts available" applies to this part; it meets RoHS Directive 2011/65/EU requirements with lead-free terminations and halogen-free molding compound - confirmed in the Ordering Information section.
Can the 71256S35TDB be used with 3.3V logic interfaces?
No, the 71256S35TDB is strictly a 5V device with TTL-compatible inputs (VIH = 2.2V min, VIL = 0.8V max) and outputs (VOH ≥ 2.4V, VOL ≤ 0.4V at 8mA), but it requires VCC = 4.5–5.5V and has no 3.3V supply option. Interfacing with 3.3V controllers requires level translation on all address, data, and control lines - the 71256S35TDB itself does not support mixed-voltage operation.
71256S35TDB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- -
- Package/Case:
- 28-CDIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Volatile
- Memory Format:
- SRAM
- Technology:
- SRAM - Asynchronous
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 35ns
- Access Time:
- 35 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-CDIP
71256S35TDB FAQ
1.How can I place an order for 71256S35TDB through Aetrix?
Please submit a Request for Quotation (RFQ) for 71256S35TDB on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for 71256S35TDB reliable?
The price and inventory of 71256S35TDB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71256S35TDB is usually 5 days.
3.What payment methods are accepted for 71256S35TDB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71256S35TDB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 71256S35TDB?
71256S35TDB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 71256S35TDB order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for 71256S35TDB?
For technical support, including 71256S35TDB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71256S35TDB requirements.
6.How does Aetrix verify that 71256S35TDB is sourced from the original manufacturer or authorized distributors?
All 71256S35TDB products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 71256S35TDB meets industry standards.
7.What is the process for return or replacement of 71256S35TDB?
All 71256S35TDB units undergo pre-shipment inspection (PSI). If there is an issue with 71256S35TDB, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The 71256S35TDB part is unused and in its original packaging.
Return procedure for 71256S35TDB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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